The present invention relates to pharmaceutical matrix pellet formulations providing an adequate drug release profile. The matrix of said pellets is formed from: (a) a hydrophilic compound selected from the group consisting of starch, a starch derivative and a mixture thereof, and (b) a hydrophobic compound selected from the group consisting of wax, microcrystalline wax and a mixture thereof.
It is known to provide pellets with a coating, for example an outer polymer coating, for obtaining a specific drug release profile. The coating of pellets with a polymer layer is time consuming. Furthermore, many parameters (such as the layer thickness, the film quality, film aging, the processing parameters, microdefects in the film, etc . . . ) have an influence on the drug release rate. As the exact control of all these parameters is difficult, pellets have no precise drug release, but have a drug rate varying within a certain range. Furthermore the preparation of the known coated (controlled release) pellets requires several production steps.
So as to try to avoid this drawback, the man skilled in the art would suggest to use a thick polymer layer coating the pellets. The use of thick coating layer is however detrimental as it reduces the release rate.
The aim of the present invention in to solve the problems due to the use of outer polymer coating on pellets. The invention provides matrix pellets not provided with any polymer coating, but having the desired release profile.